MTU size in Switch wrf to MPLS

[prashantdwivedi]

Hi All,

As we all know mpls frame size is 1512  byte and normally our switch(3550,3560)support 1500 byte mtu size.

then how it accept giant mtu and process it further especially in case of MPLS.

thanks a lot.

[Jung Sun Lee]

Most of DSBU switches MTU is configured globally. There are 3 types of MTU configuration.

1. System MTU: MTU used by fast ethernet ports or L3 routed interfaces.

2. System jumbo MTU: used by L2 gig ethernet ports that are switching/bridging pacekts. In case of MPLS/EoMPLS, this is what you need to configure to support jumbo frames.

3. MPLS MTU: used on MPLS configured ports or SVIs.

If you are not configuring MPLS on 3550/3560, then please configure "system mtu jumbo xxx".

NOTE: Once you change system mtu, switch is required to be reloaded.